Mercury Light and Spectrum
Name: Don W.
Date: Wednesday, June 26, 2002
Why does the mercury light from public lighting appear
blue, even though there are yellow and green lines also appearing in the
Mercury has a rich atomic line spectrum. The "blue" appearance is due to
the fact that the emission line at 435.8 nm is much more intense than other
emission lines in the visible region. In the design of mercury lamps the
conditions of pressure, and other design parameters are optimized to
maximize its output at this wavelength. An analogous situation occurs with
"sodium" street lamps that have a characteristic yellow appearance due to
the intense sodium emission.
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Update: June 2012